National Repository of Grey Literature 9 records found  Search took 0.00 seconds. 
Analysis of stock market sentiment with social media
Čermák, Vojtěch ; Baruník, Jozef (advisor) ; Vacek, Pavel (referee)
In the thesis, we explored prospects of extracting sentiment contained in Twitter messages. We proposed novel approach consisting of directly predicting the volatility on stock market by features obtained from the text documents using suitable document representation. We compared the performance of standard document vectorisation methods as well as a novel approach based on aggregating word vectors created by word embeddings. We showed that direct modelling of a market variable is possible with most of the proposed vectorisation techniques. In particular, the strong predictive power of aggregated word embeddings suggests that they are excellent sentiment representation, because they are independent of message volume and they capture well the semantical information in the tweets. Besides, our findings suggest that aggregating word embeddings vectorisation is viable approach even for large documents.
Regulation of floral initiation in woody perennials
Čermák, Vladimír ; Mašková, Petra (advisor) ; Čermák, Vojtěch (referee)
Floral initiation is an important process for temperate woody perennials that affects the subsequent development of the flower. Although this process is well known in annual plants such as Arabidopsis thaliana, not much research has been done in woody plants. This review summarizes the knowledge about mechanisms of flowering induction in woody perennials, compared to the findings in model plants, especially A. thaliana, including factors involved in the regulation of the flowering process. In particular, FT-like genes and TFL1-like genes, which play an important role in the regulation of flowering induction, are discussed in detail. In temperate woody plants the dormancy period follows the floral induction before the floral development. Periodic regulation of this stage is controlled endogenously and, in addition to other factors, it is affected by expression of DAM genes. The genetic mechanisms regulating endodormancy release in woody perennials are similar to vernalization in herbs. Better understanding of processes such as the floral induction and endodormancy release can help us to develop cultivars with a modified flowering time.
Kinematic record of Jurassic obduction of oceanic crust in the West Carpathians
Čermák, Vojtěch ; Jeřábek, Petr (advisor) ; Vojtko, Rastislav (referee)
English abstract The bachelor thesis is focussed on problems of Jurassic subduction of Meliatic ocean in the region of the Western Carpathians. This oceanic domain opened during the Middle Triasic and closed at the end of Middle Jurassic. The existence of the oceanic domain in the Western Carpathians is documented by sedimentary rocks of oceanic origin glaucophane bearing basalts and serpentinized ultramafic rocks preserved in the area of the presumed suture zone. The chemical composition of metabasalts corresponds to the transition between the basalts of mid-oceanic ridges and basalts of island arcs. The metabasalts underwent high-pressure, low- temperature metamorphism, which proves their drag into to substantial depths during subduction and were later exhumed to structurally lower parts of the accretionary wedge. The research was focussed on identification of deformation record in units of the southern Gemeric Superunit, Meliata Unit (Borka Nappe) and Silicic Nappe. Four deformation events D1 - D4 were identified on the basis of structural analysis in the studied area. Deformation events D1 - D3 show distinct record in different units and are associated with roughly east- west direct of compression connected with the subduction of Meliatic oceanic plate, exhumation of its parts into an accretion complex...
Kinematic record of Jurassic obduction of oceanic crust in the West Carpathians
Čermák, Vojtěch ; Jeřábek, Petr (advisor) ; Vojtko, Rastislav (referee)
English abstract This thesis is specialised in problems of Jurassic subduction of meliatic oceanic area in the region of the Western Carpathians. This oceanic basin opened during middle trias and closed during middle Jurassic. Sedimentary rocks of oceanic origin and glaukofanitised basalts in the area of the presumed suture zone prove the existence of this oceanic basin. Metabasalts, whose chemism corresponds with the transitional composition between the basalts of mid-oceanic rifts and those of island arc, underwent high-pressure, low- temperature metamorphosis, which proves their being pulled to substantial depth during the subduction and later exhumed to lower parts of accretionary wedge. The practical part of this thesis is aimed at presentation of data gained from measurements of crystallographic orientation of calcite grains in marble appearing together with metabasalts in the Bôrka nappe. Key words: Western Carpathians; Bôrka nappe; Turnaicum; Silicic nappe; subduction; suture
The role of histone post-translational modifications in the regulation of gene expression in plants
Chromý, Jakub ; Čermák, Vojtěch (advisor) ; Holá, Dana (referee)
Chromatin structure, gene expression and consequently many important aspects of the plant development are under control of epigenetic regulation. Within epigenetic regulation, histones and their modifications play a pivotal role. The N-terminal tails of histones are dynamically modified by covalent post-translational modifications (PTMs). These modifications are key regulators modulating chromatin structure and thus regulating gene expression. In angiosperms, one of the processes finely regulated at the epigenetic level is the flowering. Flowering represents a very complex process, that is relevant for the study of epigenetic regulation as well as for practical application. In this work, I summarize current knowledge of the role of histone PTMs in the regulation of gene expression in plants, focused predominantly on two key regulators of flowering in Arabidopsis - FLC and FT.
Efficiency, predictability and liquidity in the commodity futures markets
Čermák, Vojtěch ; Krištoufek, Ladislav (advisor) ; Čech, František (referee)
This thesis examines efficiency of several CME commodity futures and its relation to market liquidity over the ten years period. The goal is to find ARMA model that is better than white noise in terms of forecasting power and carry out analysis of market liquidity if we find such model. This is done by comparing selected ARMA models to white noise. In order to do that, we use Diebolt - Mariano test on forecast errors obtained by pseudo out - of - sample analysis using rolling window with re - estimation. Concern of furhter analysis are factors, that can influence the DM statistics. Main findings are, that we are able to find such ARMA model for small enough time period within the ten years period for almost all commodities. For most commodities, this sub period is not long enough to violate efficient market hypothesis. Only for palladium and lean hog futures this period is longer than one year. These two futures shows strong signs of inefficiency, as its predictability is not out - weighted by liquidity restrictions.
Study of the mechanism of posttranscriptional and transcriptional transgene silencing in tobacco BY-2 cell line
Čermák, Vojtěch ; Fischer, Lukáš (advisor) ; Moravec, Tomáš (referee)
The RNA interference is a mechanism, which allows cells to regulate their genes functions, to establish and maintain heterochromatin and to defend them against invasive nucleic acids. In plants, RNA interference is initiated by double-stranded RNA, which is processed by Dicer into small RNAs, usually 20-24nt long. These small RNAs form a complex with Argonaut protein that participates in different processes based on sequence complementarity. This complex can guide mRNA cleavage, translation blocking and chromatin modifications, resulting either into posttranscriptional silencing (by preventing translation of already existing mRNA, PTGS) or transcriptional silencing (by preventing transcription of mRNA, TGS). The first step of this thesis was to establish different ways of triggering PTGS and to evaluate their functionality and efficiency. The next step was a preparation of a system which would allow to study the transition from posttrancriptional to transcriptional silencing. These so called "indicator lines" should allow to observe the timing and dynamics of this process by utilizing fluorescent proteins. This system is also going to enable to evaluate, how different factors are involved in this process - one of the factors is RNA-dependent RNA polymerase 6 (RDR6) which plays an essential role in...
RNA interference in plants
Čermák, Vojtěch ; Kulich, Ivan (referee) ; Fischer, Lukáš (advisor)
The process of RNA interference allows cells to regulate functions of their genes. This process is usually initiated by the presence of double-stranded RNA within a cell. Such double-stranded RNA is diced by a specific protein called Dicer into duplexes of small RNAs, usually 20-25 nucleotides long. Single-stranded small RNAs, released from the duplexes, are the heart of RNA interference and they can be categorize into several groups according to their biogenesis. There are two groups of small RNAs in plants: miRNA and siRNA. Small RNAs can associate with a protein called Argonaut and guide it to the target molecule on the bases of sequence complementarity. The Argonaut-small RNA complex can act on itself or it can interact with other proteins in a wide spectrum of processes. The complex can slice the target mRNA (which can be handled by the sole Argonaut and small RNA), it can suppress translation or it can direct chromatin modifications. The phenomena of RNA interference can be found in almost all Eukaryotes where it can serve many functions, for example it can control cell differentiation, participate in stress responses, direct changes in chromatin and defend the organism against viruses. A diverse set of operating modes of RNA interference can be found in plants, which we are only at the...

See also: similar author names
9 Čermák, Vladimír
4 Čermák, Václav
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